increase precision of hyperu
Fixed docs for return values of scipy.sparse.linalg.eigsh

v[:, i] (not v[i]) is indeed the eigenvector corresponding to w[i].
The docstring for eigs, also given in this file, is already correct.
Merge pull request #2915 from garrison/eigsh-doc-patch

DOC: sparse.linalg: fixed docs for return values of scipy.sparse.linalg.eigsh
Merge pull request #2909 from gertingold/gh-2287

BUG: special: increase precision of hyperu
DOC: clarify the docstring of randint

Also fix the 4th moment.
ENH: moments for the zipf distribution